Mayor Stephanie Rawlings-Blake joined Baltimore law enforcement leaders Thursday to pledge "renewed energy" in cracking down on crime, highlighting an initiative to boost cooperation between state and federal prosecutors.

The move doubles the number of city prosecutors who can try cases in federal court — where penalties are often stiffer for repeat offenders — by bringing on two new state's attorneys to focus their efforts on violent crime in East and West Baltimore. The new positions were approved this year as part of the city budget that went into effect this month.

At a news conference, Rod J. Rosenstein, the U.S. attorney for Maryland, said the funding decision was indicative of Baltimore's resolve to prevent violent outbursts like the one that recently saw dozens shot and 23 killed over a span of three weeks.

"It was only 18 months ago that we achieved a result that many people thought was impossible — lowering the annual murder rate in Baltimore below 200," Rosenstein said. "We intend to do that again."

The moves help bolster Rosenstein's ranks, which have been reduced because of federal budget cuts. Even so, his office has been taking on more gun cases through the Exile program, from 151 defendants in 2006 to 239 in 2011.

"The two special assistant United States attorneys will enhance our ability to identify the most dangerous offenders and prosecute them in the federal system," Rawlings-Blake said.

Baltimore State's Attorney Gregg L. Bernstein said veteran candidates from his office are being vetted and that their positions will be filled.

"We're not only doubling this crime-fighting initiative but doing it in a targeted, strategic way by assigning these two prosecutors to specific areas in the Eastern and Western [police] districts where we're seeing the most violence," Bernstein said.

Batts said those changes reflected the understanding of the department he's gained since taking over last fall. But some of the moves drew concerns from City Council members, who called for continuity after the recent violence.

Homicides and nonfatal shootings have increased in Baltimore compared with the same period last year.

Nonfatal shootings over the past month are up 115 percent compared with the same period last year. If that pace continues, it would reverse six straight years of declines in nonfatal shootings.

Bernstein said that in recent weeks, representatives from the U.S. attorney's office, the state's attorney's office and the police have been conducting high-level meetings to develop investigations and take down individuals and groups that they believe are responsible for much of the city's violence.

"We are hopeful these investigations will lead to successful prosecutions," Bernstein said.

State and federal prosecutors confer often about state cases that could be pursued at the federal level, where prosecutors have a near-perfect conviction rate and jurors are pooled from around the state. Federal prosecutors often obtain longer sentences against defendants who are believed to be involved in violence but are charged with lesser crimes.

For example, because of his previous felony convictions, a man thought to be at the center of a drug war in 2009 was sentenced to four years in prison after police found a box of ammunition in his bedside drawer.

"Law enforcement is always working with a sense of urgency, but we're working with a renewed sense of urgency to try to head off the violence," Rosenstein said. "We don't want to be in the business of prosecuting murderers — we want to be in the business of preventing murders by arresting criminals and intervening in violent gangs before they commit illegal criminal activity."

Rosenstein called on residents to help police by coming forward with tips, and he vowed that authorities would protect them.

"If we have your cooperation, we're going to commit the resources to make sure you're safe, to make sure your children are safe, to make sure the streets of Baltimore are secure," he said. "We aim not just to bring the murder rate below 200 [annual victims] but to keep it falling."

Howard County police said Timothy Mark Fuller, the man they claim shot his sister-in-law before officials found her body inside a burning trailer in Elkridge Saturday, was arrested Sunday morning in Florida.